test/built-ins/Array/prototype/filter/15.4.4.20-6-7.js


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// Copyright (c) 2012 Ecma International.  All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
esid: sec-array.prototype.filter
es5id: 15.4.4.20-6-7
description: >
    Array.prototype.filter returns an empty array if 'length' is 0
    (subclassed Array, length overridden with obj w/o valueOf
    (toString))
---*/

foo.prototype = new Array(1, 2, 3);

function foo() {}
var f = new foo();

var o = {
  toString: function() {
    return '0';
  }
};
f.length = o;

// objects inherit the default valueOf method of the Object object;
// that simply returns the itself. Since the default valueOf() method
// does not return a primitive value, ES next tries to convert the object
// to a number by calling its toString() method and converting the
// resulting string to a number.

function cb() {}
var a = f.filter(cb);


assert(Array.isArray(a), 'Array.isArray(a) !== true');
assert.sameValue(a.length, 0, 'a.length');